Free fall bottom sampler

ABSTRACT

A bottom sampler to obtain a sample of the bottom of a body of water. A pair of clam shell jaws are pivotally connected to the base of an upright frame of the sampler. Hollow buoyant spheres are retained within the upright portion of the frame. The jaws are latched in an open position against the bias of resilient elements which close the jaws when the latch is released in response to impact with the bottom. Two weights, one on the back of each jaw stabilize the sampler during descent and fall off when the jaws close. A camera located within one of the hollow spheres photographs the bottom of the body of water from which the sample is taken. A unique signal-flare and smoke producing device automatically actuated when the sampler returns to the surface. Other day or night signal devices such as a radio or flasher can also be used and provision is made to attach such devices to the sampler.

United States Patent Walthier et al. Aug. 7, 1973 [54] FREE FALL BOTTOMSAMPLER 2,784,273 3/1957 Binford 200/84 [75] Inventors: Thomas N.Walthier; Andre Marcel Rosefelder; Clifford E. Schatz, all of PnmaryEmmmerl9hn Hora" New York Attorney-John C. Smado [73] Assignee: BearCreek Mining Company, Salt Lake City, Utah [57] ABSTRACT [22] Filed Oct16 1970 A bottom sampler to obtain a sample of the bottom of a body ofwater. A pair of clam shell jaws are pivotally [21] Appl. No.: 81,222connected to the base of an upright frame of the sam- Related U sAppncation Data pler. Hollow buoyant spheres are retained within the[62] D fs '7 792 M h 8 1968 P t N upright portion ofthe frame. The jawsare latched in an 3 2 5 23 arc a open position against the bias ofresilient elements which close the jaws when the latch is released inresponse to impact with the bottom. Two weights, one on the back of eachj stabilize the sampler during [58] Fie'ld 350/l79 scent and fall offwhen the jaws close. A camera lo- 350 l w 200/84 cated within one of thehollow spheres photographs the bottom of the body of water from whichthe sample is taken. A unique signal-flare and smoke producing de- [56]Reerences Cited vice automatically actuated when the sampler returnsUNITED STATES PATENTS to the surface. Other day or night signal devicessuch 3,084,433 4/1963 Kaatz 350/175 as a radio or flasher can also beused and provision is made to attach such devices to the sampler.

mit v 2,249,418 7/l94l Chambers 200/84 15 Claims, 12 Drawing Figures i iT\ PATENTED 7 3. 750. 547

sum 2 05 4 HNDRE M. ROSFELOER BY CLIFFORD E. Sci

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FREE FALL BOTTOM SAMPLER This is a division of applicationSer.No.711,792 filed Mar. 8, 1968, now US. Pat. No. 3,572,129.

This invention relates generally to a bottom sampler to obtain a sampleof the bottom of a body of water, and more particularly to such asampler of the recoverable free-fall type which does not require aretrieving line between the sampler and the vessel from which it islaunched or dropped.

More specifically, the invention relates to a unique free-fall seabottom sampler having clam shell type jaws which dig into and grab asample of the bottom and the sampler then returns to the surface of thewater with the sample. Although the sampler of this invention has otheruses, it is of particular utility for obtaining samples of an oceanbottom to determine the presence of manganese nodules in anticipation ofsub-sea mining.

Among the features of the bottom sampler of this invention are a pair ofclam shell jaws adjacent the bottom of an upright frame, floatationmeans in the form of hollow glass or plastic spheres retained by theframe, resilient means to close the jaws to obtain a sample of the oceanbottom, and a latch assembly actuated in re sponse to impact of thebottom sampler with the ocean bottom to release the jaws so they closeunder the influence of the resilient means. The jaws are so arranged sothat the weights which cause the sampler to sink to the bottom, aremerely supported on each of the jaws and these weights create forcemoments which assist the resilient means during initial closing ofthe'jaws. The weights fall off the jaws at an intermediate point duringclosing and hence, the sampler is returned to the surface by thefloatation devices. One of the spheres is transparent and provides ahousing for a flash bulb equipped camera to photograph the portion ofthe ocean bottom from which the sample is taken. The camera is operatedin a unique manner.

A significant advantage of the sampler of this invention over thepreviously known coring type samplers is that this sampler takes asignificantly larger sample than these prior known devices. In oneembodiment, the back of each jaw of the sampler is completely closed andthe entire grabbed sample is retained. In another embodiment, a meshsack which allows washing out of the fines, extendsacross the back ofeach jaw and clean samples of the modules are recovered at the surface.

Additional features and advantages of the bottom sampler includes astructure which sinks in the water in a stable vertical positionthroughout its travel to the bottom. Such vertical stability isattributable, at least in part, to the location of the ballast weightsadjacent the bottom of the sampler and the location ofthe floatationspheres above the weights. A distinct advantage of the arrangement isthat the sampler is actuated to allow the jaws to close wholly by amechanical system which is completely fool proof. Hence, even ifamalfunction occurs the sampler will return to the surface where it canbe recovered. Even where the sampler encounters a rough or uneven bottomwith substantial slant, at least a small sample is taken and the samplerreturns to the surface where it can be recovered. A known disadvantageof the coring type samplers is loss of the sampler where the coringdevice is driven into the bottom at an angle. Since the sampler of thisinvention does not rely on a coring tube or other similar device to takethe sample its reliability is far better than the prior known devices.

The signal and flare device, which forms a portion of this invention,includes a unique mechanical blocking mechanism to prevent its actuationuntil the bottom sampler returns to the surface.

Numerous other features and advantages of the bottom sampler of thisinvention will become apparent with reference to the drawings which forma part ofthis specification and wherein:

FIG. 1 is a pictorial view of the sampler of this invention;

FIG. 2 is a partial enlarged side elevational view, with portions insection, of the jaw release mechanism;

FIG. 3 is a sectional view taken along lines 3-3 of FIG. 2;

FIG. 4 is a partial side elevational view, with portions thereof brokenaway, of the upper portion of the bottom sampler of this invention, andshows the mode of mounting a camera in the transparent sphere, and thefluid lens of the sphere;

FIG. 5 is a side elevational view showing a second type ofjaw of thesampler, and showing the position of the various parts of the samplerimmediately after the jaws are released; I

FIG. 6 is a view corresponding to FIG. 5 but showing the jaws closed;

FIG. 7 is a side elevational view of the flare and smoke signal deviceof the bottom sampler;

FIG. 8 is a sectional view taken along lines 88 of FIG. 7;

FIGS. 9-l1 are side elevational views of the signal device, with FIG. 9showing forces acting on the device during descent of the sampler, FIG.l0 showing forces acting on the device during ascent of the sampler, andFIG. 11 showing the signal device actuated; and

FIG. 12 is a wiring diagram of the camera shutter operating circuit ofthe bottom sampler. v

Referring now to the drawings in detail and particularly to FIG. 1,there is shown a sampler l constructed in accordance with this inventionhaving a frame 2 including a base 3 and an upright portion or cage 4.Pivotally connected to base 3 are jaws 5 and 6 which are movable fromthe open position of FIG. 1 to the closed position of FIG. 6.

'Jaws 5 and 6 are normally urged to the closed position by a pluralityof resilient elements 7 which are advantageously formed from surgicaltubing (of the type used in underwater spear guns) because of its highstrength and elasticity. Jaw actuating mechanism 8 interconnects thejaws when in the open position of FIG. 1 and maintains the jaws openuntil the bottom sampler hits the bottom of the body of water from whichthe sample is to be taken, whereupon the jaws are released, and close ina manner which will subsequently be described in detail.

Disposed within upright portion 4 are hollow spherical buoyant elements9-11.

Weights l2 and 13 are supported, respectively, on jaws 5 and 6 and causethe bottom sampler'to sink to the bottom of the body of water in whichit is dropped. The weights fall off when the jaws close to take a sampleof the bottom, and the sampler is buoyed upwardly by spheres 9-11 andreturns to the surface.

A combined flare and smoke producing device 14 connected to the top ofupright portion 4 of the frame is actuated when the sampler surfaces andprovides a signal to assist locating the sampler.

Base 3 is generally rectangular and includes horizontally elongated,upright rectangular side plates and 16 in spaced apart parallel relationto each other and connected together by tubular cross members 17-19which extend perpendicularly between the side plates. Tubular member 17is welded at its ends to side plates 15 and 16 at a location adjacentthe top edge of the side plates but centrally along their length. Tube18 is welded to the side plates so it extends slightly below the bottomedge of the plates and is located adjacent one end of the plates. Tube19 is similarly welded to the side plates adjacent the opposite end ofthe base. As is seen from FIG. 1, the tubular cross members 17-19 areeach parallel with each other, and cross members 18 and 19 are disposedin the same horizontal plane. Tubular members 18 and 19 cooperate withside plates 15 and 16 to provide a base 3 of generally rectangularconfiguration as viewed in plan.

Welded to tubular cross member 18 and curving inwardly and then upwardlyfrom the tubular member are a pair of tubular connectors 20 and 21 whichextend approximately one fourth the height of upright portion 4 of theframe. Connectors 20 and 21 are fixed to tubular cross member 18 bywelding and are in spaced apart parallel relation to each other. Asecond pair of tubular connectors 22 and 23 curve, first inwardly andthen upwardly, in the same manner as connectors 20 and 21 and are weldedto tubular cross member 19 so they extend upwardly in spaced parallelrelation to connectors 20 and 21. The arrangement is such that the upperends of the connectors form a rectangular array.

Upright portion 4 of the frame includes elongated upright tubes 24-27,the lower ends of which extend respectively into the upper ends oftubular connectors 20-23 and are secured against longitudinal movementby lock pins or screws 28. Each screw 28 extends through the wall of atubular connector and through the wall of an upright tube to key thetubes to the connector.

The upper ends of upright tubes 24-27 extend through sleeves 29 fixed toa clamping ring 30. Sleeves 29 are secured to the clamping ring withtheir axes vertical and in the same rectangular array as that ofconnector tubes 20-23 and are spaced vertically above the connectortubes. It will be observed with reference to FIG. 1 that upright tubes25 and 26 terminate at the clamp ring whereas tubes 24 and 27 extend asubstantial distance above the ring. As shown at FIG. 4, screws 31threaded into sleeves 29 hold the clamp ring in position ontubes 24-27.

With reference to FIG; 4, three retaining studs 32-34 are fixed to clampring and project radially out wardly from the ring in equally spacedcircumferential relation to each other. Each retaining stud has anenlarged head 35 by which a clamp assembly 36 is connected to clamp ring30. Clamp assembly 36 has three equally spaced arms 37-39 having upperends secured to a threaded boss 40 positioned above the vertical axis ofsphere 9. Each arm, generally follows the curvature of sphere 9, hasopenings 41-43 serially located adjacent the ends of the arms, theseveral openings of the respective arms each being spaced the samedistance from the ends of the arms. Openings 41-43 are each slightlylarger than the heads 35 of studs 34. Extending through threaded boss 40is a clamp bolt 44 which engages a bushing 45 on a resilient suction cup46 pressed against the upper end of sphere 9. Suction cup 46 acts as acushion between the sphere and clamp bolt 44 and prevents slipping.

Sphere 9 is comprised of two identical hemispherical shells, includingan upper hemisphere 47 and a lower hemisphere 48, which are tightly heldtogether by clamp assembly 36 and clamp ring 30. As shown at FIG. 4, thehemispherical shells abut along a horizontal joint 49. The surfaces ofthe halves at the joint are smoothly polished. A seal is providedbetween the abutting surfaces and may take the form of a thin metal orplastic gasket or silicone grease. Clamp ring 30 has an inside diameterslightly less than the diameter of sphere 9 so that lower hemisphere 48seats in the clamp ring. Thus, when pressure is applied to upper half 47of sphere 9 by tightening clamp bolt 44 the hemispheres 47 and 48 willbe tightly pressed together and sealed against leakage of water into thesphere. By making openings 41-43 slightly larger than the enlarged heads35 of studs 32-34 it is merely necessary to unthread clamp bolt 44several turns so that heads 35 of the studs can clear the openingswhereupon the arms 37-3 9 may be flexed outwardly and the clamp assembly36 removed. Then upper hemisphere 47 can be lifted to open the sphere.Installation of clamp assembly 36 to close the sphere can beaccomplished with equal facility. Resilient pads 48' (FIG. 4) betweenarms 37-39 and hemisphere 48 provide cushions to prevent damage whenclamp assembly 36 is tightened. When the sampler is used indeep water,the high pressures encountered cause sphere 9 to shrink with the resultthat lower hemisphere 48 may then slip through clamp ring 30. This isprevented by retaining straps 49 (shown at FIG. 1 only) of which thereare three, and which, are

welded to clamp ring 30 at equidistantly spaced locations, follow thecurvature of lower hemisphere 47, and are joined by welding adjacent thepole of the hemisphere.

Hemispheres 47 and 48 are advantageously formed from relatively thickglass or transparent plastic such as PLEXI-GLASS or LUCITE which havegood compressive strength. Mounted in the bottom of hemisphere 47 is aflat transparent plate 50 of circular outline which is cemented to theinside of the hemisphere.

'A reinforcing strut 51 with a flat top edge and a curved lower edgeconforming to the curvature of the insideof hemisphere 47 extends acrossthe center of plate 50 between the plate and the hemisphere to brace theplate against bending. Mounted on plate 30 is a bracket including clamps52 and53 which engage. the opposite ends of and hold a camera 54securely to the plate. Plate 50 is so mounted in hemisphere 48 that theplate extends at an angle of 30 to horizontal when the sampler is in itsnormal upright position. Lens 55 of camera 54 is parallel with plate 50and thus, the axis of the lens extends at a angle with horizontal. Itwill be observed with reference to FIG. 4 that the camera is locatedessentially midway between adjacent upright tubes as well as betweenstraps 49 and thus, can photograph a portion of the bottom of the bodyof water from which a sample is taken. Camera 54 advantageously has aself-contained flashbulb unit 56 synchronized with the shutter of thecamera to illuminate the portion of the bottom which is photographed.

The space between plate 50 and the insidesurface of hemisphere 48 isfilled with a transparent fluid 53' to provide a fluid lens 54'. Thefluid lens provides a unique way to eliminate the distorting effectofimperfections in the inner surface of the hemisphere and also avoidsdistortion of a picture taken by the camera due to the curvature ofthehemisphere. The refractive bottom occurs. The fluid lens 54 has twosignificant functions, first,it eliminates the effect of imperfectionsof the inner surface of the hemisphere on light travelling from theinside to the outside of the hemisphere, and secondfit eliminatesconsiderably distortions due to the curvature of the hemisphere.

Where complete elimination of distortion is required, a ring 55 of adiameter essentiallythe same as the diameter of plate 50 is cemented tothe outside of hemisphere 47 with its axis aligned with the center ofplate 50. Fitted into ring 55 is anouter plate 57' which is spacedslightly from the outside surface of hemisphere 47. Thus, there is asecond space between the outside surface of the hemisphere and outerplate 57. Where the ring and outer plate'are used, both the spacebetween plate 50 and the inside of the hemisphere, and plate 57' and theoutside of the hemisphere are filled with a transparent fluid53' of thesame index of refraction as the hemisphere material. When the spaces areso filled with material of the same refractive index, the hemispherematerial'is eliminated optically from the fluid'lens. Thus, nodistortion at all occurs because the camera lens is parallel to bothplates 50 and 57' and thus, the distorting effectsof refraction arecompletely eliminated by the fluid lens 54'. A'dvantageously, no highpressure seals are required since the lens does not have parts thatextend through the hemisphere 47. In addition, since the space withinring 5 5' is fllled with a liquid (which is incompressible), highexternal pressures will not damage the liquid lens. Strut 51 isadvantageously painted completely black. The absorbtive effect of ablack color on light substantially eliminates reverberation oflightthrough the fluid 53'jfrom flash unit 56 to the lens of camera 54, whenthe'flash unit is fired.

The shutter'ofcamera 54 is-actuated in a unique manner. As shownirfFlGS. 4 and 12, a solenoid 57 is connected in series circuit relationwith a switch 58 and a battery 59, all contained within sphere 9.Solenoid 57' has a plunger 60 connected to the shutter of the camera tooperate the shutter when solenoid 57 is energized. Switch 58 is amagnetically actuable glass enclosed reed switch, of the normally opentype, having a movable magnetic contact 61 and a stationary contact 62.Switch 58'is mounted-on the inside surface of hemisphere 47. Engaginghemisphere 48 on the outside immediately opposite switch 58 is anactuator tube 63 formed of nonmagnetic material such as stainlesssteel,which is readily weldable and has anopen top end and a bottom end with asmall, centrally located opening therein. Located within tube6 3 is acylindrical magnet 64and a spring 65 disposed between the magnet and thelower end of tube 63. A string 66 is'connected to the bottom of themagnet and extends through the opening in the bottom ofthe tube. String66 is maintained taut-(before the jaws are released) to hold magnet 64in a lowered position within tube 63, and spring 65 is undercompression. Since magnet 64, in this position, is substantially belowswitch 58, the switch contacts remain open. However, when the string 66is released, spring 65 forces the magnet upwardly and switch contacts 61and 62 close asmagnet 64 passes by switch 58. .With string 66 released,magnet 64 ulti-' mately assumes an upper position above switch 58 andadjacent switch 58', the switch 58 controlling a radio or a flasher (notshown) inside the hemisphere to facilitate recovery, as will beexplained later.

Jaw 5 is fabricated .from a pairofpa'rallel side plates 67 and 68 spacedapart a distance slightly greater than the distance between the outsidesurfaces of side plates and 16 of base 3. Side plates 67 and 68 are eachformed from heavy guage sheet metal and have rear edges 69 and 70respectively, which form therear face ofjaw 5. Side plates 67 and 68also have front edges 71 which form a front face of jaw 5, the frontedges being sharpened along a substantial portion of their length toform aknife edge 72which assists cutting or slicing a sample whenthejaws close. Side plates 67 and68 each have a first side edge 73 whichextends at an acute angle to front edge 71 and merges with both thefront edge and the rear edge of the respective plates at smoothlyrounded corners 74 and 75. At the opposite ends of side plates 67 andf68is aside edge 76 which extendsgenerally perpendicularly to front edge7]. Adjacent corners of side plates 67and68'is a tubular cross-member 77which is welded to the inwardly facing surfaces of the side platespBolts78 and 79'which pass through openingsin "the sideplates adjacent corners74,75 pivotally mount jaw 5 on' the base. A toothed cutter 80 extendsbetween side plates 67 ,and 68; is secured to the side plates and liesagain st side edge-76, cutter blade 80 isso mounted on the side platesthat it is tangent to a circle about the pivotal axis of the jaw. V

Rear edges 69 and 70 of side plates67 and 68 each slope first downwardlytoward front edges 71 of the plates and then curve arcuately upwardlybefore merging with side edge 76 to form upwardly facing arcuate cradles82 and 83 in the respective side plates.

As shown at FlGf l, weight 12 has a cylindrical body 84 with enlargedcylindrical-ends 85 and 86. Bddy 84 is slightly longer than thedistance'between plates 67 and 68 and thus, the inwardly facing transversesurfaces 87 of ends 85 and ,86 extend b'eside the outer surfaces of sideplates 67' and 68. v n I Jaw6 is identical to jaw 5 and iii the positionshown at FIG. 1, jaw 6 is merelyjjaw 5 rotated 180? ina horizontalplane. Thus, jaw 6 includes spaced apart side plates 87 and 88,across-member 89'extending between secured side plates, and a sampleslicing or cutting blade 90 secured to and extending between the sideplates. The side plates 87 and 88 have front edges 91 with sharpenedknifeedges'92,-and rear edges 93 each having a weight receiving cradle.94 which-faces upwardly when'the jaws are in the open position ofFIG. 1. Jaw 6 is pivotally mounted on base 3with bolts 94. Weight 13 isidentical toweight l2 and has a body 95 with enlarged ends 96and 97.Ends 96and 97 extend on each side of side plates 87 and 88in the samemanner as described for weight 12, when weight 13 is placed in cradles94.

As shown in FIG. 1, jaws and 6 have both an open front and an open back.The open back of jaw 6 is closed by a sample retaining sack or bag 98which extends across the side plates and is secured to them at the rearedges 93. Sack 98 also extends to and is secured to rear edge 99 ofcutter blade 90. A series of spaced apart openings formed adjacent therear edges of the side plates and cutter blade 90 provide for sewing ortying the sack to the jaw with cord 100 by threading the cord throughthe openings. Sack 98 is formed from a flexible imperforate web or canalso be net or other mesh material sewn and dimensioned to bulgeoutwardly when the jaws are closed, as shown at FIG. 6. Advantageously,sack 98 is formed from a flexible non-elastic material such as canvas orfine mesh fish net. An identical sack 101 extends across the rear faceof jaw 5 and is similarly secured to the jaw.

FIGS. 5 and 6 show jaws 5 and 6 in modified form well as base 3 inmodified form. Here, side plates have bottom edges 17 and 18' whichslope downwardly to meet at an apex 19'. Jaw 5', while essentially thesame as jaw 5, shown at FIG. 1, has a side plate 67 with a front edge71' comprised of edges 72' and 73' which slope toward each other andmeet at a point 74'. In addition, edge 72 extends to the front edge ofcutter blade 80, edge 72' being sharpened to facilitate slicing a samplewhen the jaws are closed. Jaw 6' is identical to jaw 5' and includes amodified side plate 87 with a bottom edge 88' comprised of edges 89 and90 which extend at an angle to each other and meet at apoint 91. Edge 90extends to the front edge of cutter blade 90. Except for thesemodifications of jaws 5, 6', and base 15, the sampler of FIGS. 5 and 6is identical to that of FIG. 1.

The jaws are moved from the open position of FIGS. 1 and 5 to the closedposition of FIG. 6 by resilient elements 7. As shown in FIG. 1, thereare three resilient elements which take the form of lengths of surgicaltubing with their ends interconnected by separable fasteners 102 to formclosed bands 103l05. As shown with reference to band 105, each band hasan end 106 which is looped over cross tube 77 and extends downwardlyunder cross tube 18, a second end 107 which is looped over cross tube 89and extends downwardly across tube 19 and legs 108 and 109, which extendrespectively between cross tubes 18 and 19, with leg 109 extending.

over crosstube 17. Since the pivotalconnections for jaws 5 and 6 asprovided respectively by bolts 78, 79'

and 94' areinwardly of cross tubes 18 and 19 around which the bands103-105 extend, a substantial lever' arm is provided to assure'goodclosing of the jaws, when released.

Jaws 5 and 6 are held in the open position against the biasing action ofresilient element 7 by jaw actuating mechanism 8 located verticallyabove the horizontal center of these three.

The jaw actuating mechanism includes a horizontal connector 111 (FIG. 2)to which arms 112 and 113 are connected adjacent their upper ends forpivotal movement about horizontal axis by pins 114 and 115. As shown atFIG. 3, connector 111 is H-shaped as viewed in plan and arms 112 and 113extend into the vertical slots of the connector. Arm 112 has a notch 116adjacent its upper end, the notch being defined in part by an inwardlyextending cable retaining finger 117. Similarly, arm 113 has adownwardly facing notch 118 which is defined in part by an inwardlyextending cable retaining finger 119. Arm 112 has an elongateddownwardly extending tapered leg 120 and arm 113 has an elongateddownwardly extending tapered leg 121. The lower ends of legs 120 and 121extend into an upwardly facing recess 122 of a retaining cup 123. Anelongated rod 124 is fixed to the center of the cup and extends upwardlythrough an opening centrally located in connector 111, the rod havingits upper end threaded to permit threading the rod into a nut 125imbedded in the bottom of a suction cup 126. As shown at FIGS. 1 and 2,suction cup 126 is adhered to the bottom of sphere 11 with its centeralong the vertical axis of the sphere.

Fixed to the center of cross-tube 77 ofjaw 5 is a re taining cable 127having a loop 128 at its inner end. A cable 129 is fixed to the centerof cross-tube 89 ofjaw 6 and also has a loop 130 at its inner end.Cables 127 and 129 hold jaws 5 and 6 in the open position with loop 128extending into notch 116 and loop 130 extending into notch 118. Theinwardly extending portions of fingers 117 and 119 prevent the cablesfrom slipping downwardly off the fingers, so long as arms 120 and 121are held by cup 123. The resilient elements 7 which normally tend toclose jawsS and 6, maintain cables 127 and 129 taut and in position inthe notches. It will be noted, with reference to FIG. 2, that the lineof action of cables 127 and 129 is slightly below thereby releasing theaxis of pivot pins 114 and and thus, if retaining cup 123 is moveddownwardly, legs 120. and 121 will each pivot outwardly away from rod124, the cables will be released, and the jaws willclose tion ofresilient elements 7.

As shown at FIG. 1, sphere 10'is connected to sphere 11 by a doubleended suction cup which lies along the vertical axes of the spheres.Spheres 10 and 11 are each formed from glass or plastic and are hollowbut have considerable mass. Thus, when the sampler 1 is in the water,with the jaws open, spheres 10 and 11 exert an upward pull of the cup toretain the lower ends of legs and 121 in recess 122 of the cup. Thesamplerdescends quite rapidly through the water because of ballastweights l2 and 13 and when base 3 of the sampler strikes the bottom,spheres '10 and 11 momentarily continue to move downwardly because oftheir inertia,

as shown at FIG. 5. Retaining-cup 123 is. thus pushed downwardlyrelative to the arms (downward movement of the arms being prevented bythe cables) so the legs are released and arms are free to pivotoutwardly the cables jandallowing jaws Sand-6 to close.

As shown at FIGS. 1 and 8, flare and signal assembly,

14 is secured to the upper end of upright tube 24. The upper end offlare assembly 14 extends above the upper end of sphere 9. As shown atFIG. 8, the lower end of flare assembly 14 has a diameter slightly'lessthan the inside diameter of the tube 24 and has self cutting threads141to permit threading the flare assembly into the tube. End 140 mergeswith a cylindrical body 142 at a shoulder 143 which acts as a stop tolimit the amount the flare can be threaded into tube 24. Body 142 iscylindrical and has a reduced diameter portion 144 that merges with body142at transverse upwardly facing shoulder 145 which provides a seat forthe lower end of a closure sleeve 146. Projecting from the upper end ofportion 144 is an integral tube 147 which is internally threaded toreceive the threaded tip of a primer assembly 148 of a flare and smokecartridge 149.

under the ac- The upper end of sleeve 146 is closed.by a bushing 150having a plug portion 151 that extends into the sleeve. A transverseshoulder 152 of the bushing abuts the end of the sleeve. The bushing ispermanently and hermetically fixed to the sleeve by an epoxy cement 152solidified in opposed annular grooves around the bushing and the upperend of the sleeve, as shown at FIG. 8. Bushing 150 has a central opening153 that is Closed by a plug 154 which is friction fit in the opening. Aretaining string or wire 154 is connected between plug 154 andbushing'150 to retain the plug against loss when the'flare is fired.Suitable O-ring seals are provided between the head of plug 154 and thetop fact of bushing 150 as well as around the stem of plug 154 toprevent leakage of water through bore 153. A suitable O-ring is alsoprovided between body 142 and the lower end of sleeve 146 to preventleakage of water into the flare assembly at the joint between the body142 and the sleeve.

Body 142 has a bore 155 which terminates a short ing descent of thesampler the water through which the sampler passes exerts a force, asshown by the arrows 174, on the underside of vane 169 thereby bowing thevane outwardly and exerting a counter-clockwise moment of force onoperating assembly 165. This counter- ,clockwise moment of force merelyurges pin 170 distance from the bottom oflower end 140. A firing pin a156. is slideable in bore 155 and a helically wound spring 157 extendsbetween thebottom of-firing pin I56 andthe lower end ofbore 155.:Firingpin 156 has an upwardly facing tapered shoulder 158 and a rounded tip159, projecting upwardly up from the shoulder. v

A transverse bore .160 isformedin body 142 and has its axis tangenttothe circumferential surface of bore 155. A sear pin-161 extends into andis journalled for rotation in bore 160. Sear pin 161 has a flat 162formed therein, as by milling, the flat being aligned w'itha surfaceof-bore 155.0pposite flat 162 is a rounded portion 163 of the sear pinwhich, in the position shown, ex-

' tends radially into bore 155 and engages shoulder 158 of firing pin156 to maintain the pin in a depressed or loaded position in whichspring 157 is compressed.

Sear pin 161 has an enlarged head 164 by which the sear pin is connectedto an operating assembly 165. Operating assembly 165 includes a straightarm 166 to which head 164 is connected intermediate the ends of the arm.Fixed to the lower end of arm 166 is a flexible vane 167 which extendsupwardly and curves out wardly away from the arm. A float 168 is securedto the upper end of arm 16 6 and extends besidels leeve-146whenoperating assembly 165 is in thepositionof FIGS.

7-10 in which the firing pin is cockedalt will be noted that 'arm 166 isconnected to float 168 at a position off set to one side of the centerof the float. Connected to and extendingdownwardly from the oppositeside of float 168 isa vane 169', v'ane 169 curving outwardly. A stop pin1 70 is secured to float 168 and prevents counter-clockwise movement ofoperating assembly 165 (as shown at FIG. 9) relative to flare 14 byengagement of the pin with sleeve 146 of the flare.

Cartridge 149 includes an elongated cylinder of smoke-producing compound171 which extends upwardly within sleeve 146 from primer 148 to bushing150. Smoke-producing compound 171 has a central opening the upper end ofwhich is closed by a flare cartridge 172. Thus, when firing pin 156 isreleased it strikes primer 173 at the base of primer tube 148 andignites the primer, which in turn ignites smoke producing compound 171and flare cartridge 172.

Operating assembly 165 prevents rotation of sear pin 161 to the positionin which firing pin 156 is released, until the sampler has surfaced. Asshown at FIG. 9, dur-.

against the side of sleeve 146 and thus, float 168 remains upright andthe operating assembly does not rotate. During descent, vane 167 ispressed inwardly toward arm 166 by the water through which the samplerpasses and thus, vane 167 creates only a minimal clockwise moment of.force on operating assembly 165. Thus, operating assembly 165 preventsfiring flare 14 while the sampler is descending.

A shallow water seal arrangement is provided between bore 160 and shearpin 161.'This seal arrangement includes an annular groove 173'- in whichan O- ring 174' is seated. At shallow depths, O-ring 173' preventsleakage of water between shear pin 161 and bore 160.

In addition, ahigh pressure seal arrangement is also provided. Withreference to FIG. 7 a sealring 175 is disposed between the insidesurface of head 164 of sear pin;161 and the outer surface of body-142 ofthe lower end of theflare. In addition, it will'be-noted that sear pin161 is slightly shorter than bore 160 so that the sear pin can moveaxially in the bore. Since the area within seal ring 175 issubstantially less thanthe area of head 164 exposed to water pressure,the pressure of the water exerts a substantial force tending to pushsear pin 161 further into bore 160when the sampler-reaches a substantialdepth in the water. As aresult of the pressure and movement of the searpiniseal 175 is forced tightly against the surface of body 142 toprovide a high pressure seal and there is sufficient friction betweenseal 175 and body 142 to prevent rotation of the sear pin 161 oroperating-assembly .165 after the sampler reaches a substantial depth.

After a sample is taken and the sampler ascends, as shown at FIG..10,the water pressure gradually de creases as the sampler approaches thesurface and the friction between seal 175 and body 142 is no longersuffieient to prevent rotation of operating assembly 165. However,. asthe sampler ascends .vane 167' is bowedoutwardlyby the water as shown byarrows- 1 76,

' FIG. 10, .whereas vane 1.69 is collapsed against'theside .of float,168. .Thus, a counter-clockwise moment of force again acts on operatingassembly 165 and float 168 remains upright because of engagement-of pin170 with the side of the flare.

When the sampler surfaces flare'14 extends above the surface of thewater. Thus; there are-no external forces acting on operating assembly165.However, since float 168 is mounted at a position offset to one sideof arm 166, thefloat exerts a clockwise moment of force which causesoperating assembly to begin rotating in a clockwise direction as shownat FIG. 11. As soon as flat 162 of sear pin 161 begins to engageshoulder 158 of firing pin 156, a torque is exerted on the sear pin bythe firing pin and correspondingly the operating assembly is rapidlyrotated to the position of FIG. 11 in which firing pin 158 is free tostrike primer 173. When flat 162 is aligned with the side of bore 155,

firing pin 156 is released to strike the primer and ignite sampler wasdropped. In addition, smoke producing compound 171 produces smoke for aconsiderable length of time after the flare is fixed.

Flare assembly 14, in some instances, is quite desirable as where anumber of samplers are dropped in the same area and where ocean currentsdo not cause considerable drift of the samplers. However, a radio homingdevice can also be used to advantage. Such a homing device may take theform of a small transistor located within sphere 9, the transmitterbeing arranged to either provide a signal from the time the sampler isdropped, or to be set into operation when camera 54 is triggered or asmagnet 64 reaches a position opposite switch 58. Where such a radiotransmitter is used direction finding equipment is provided on themother ship from which the sampler is dropped, and since several shipsare frequently used to obtain representative samples of a certain areaof the ocean floor, a second direction finder on another shipfacilitates locating the surfaced sampler.

The homing device of course can take the form of a radio transmitter ina sealed package mounted on the frame of the sampler. For nighttimerecovery of the sampler after it has surfaced, a flashing light may belocated either inside sphere 9 and arranged to operate in the samemanner described for the radio homing device, or can be located in apressure type case and mounted on one of legs 24-27.

To facilitate retrieving thesampler after it has returned to the surfaceof the body of water in which it is dropped, a retrieving line 180 isadvantageously provided between the ends of legs 25 and 27, as shown atFIG. 1. This retrieving line facilitates catching the sampler with aboat hook.

OPERATION AND USE Prior to dropping the sampler into the water where thebottom is to be sampled, camera 54 is loaded and positioned in lowerhemisphere 48. The lower hemisphere is then positioned in clamp ring 30,upper hemisphere 47 is placed on the lower hemisphere, the clampassembly 36 is fitted on the clamp ring, and clamp bolt 44 is tightenedto seal upper hemisphere 47 to lower hemisphere 48.

'Next, jaws and 6 are moved to the open position of FIG. 1 using asuitable jaw-loading tool to open the jaws against the bias of resilientelement 7, and the jaws are latched inposition ,by connecting cables 127and 129 to jaw actuating mechanism 8. Since the weight of spheres l0 and11 tends to normally release jaw actuating mechanism 8 when the sampleris out of the water, the jaw actuating mechanism is temporarily lockedin the latched position of FIG. 2 with rubber bands that extend undercup 123, and are cut after the sampler is lowered into the water butbefore it is released.

Weights 12 and 13 are placed in the cradles ofthe respective jaws andsampler 1 is then ready to be used. In use the sampler is merely loweredinto the water at the desired location where a sample of the bottom isto be taken, in the upright position of FIG. 1, and is then released.With weights 12 and 13 in position, the sampler has a negative buoyancysufficient to cause the sampler to sink at a rate of 100 ft./min. to 300ft./min., depending of course on the density of the water in which thesampler is dropped, and the mass of the weights. As soon as spheres and11 are in the water, an upward pull is exerted on rod 124 and cup 123remains engaged with the arms 112 and 113 of the operating assembly.Thus, the jaws are held in the open position after the rubber bands arecut and throughout descent of the sampler.

As shown at FIG. 5, the instant sampler 1 hits bottom 177 of the body ofwater in which the sampler is dropped, the inertia of spheres l0 and 11causes the spheres to continue to move downwardly. Such downwardmovement of spheres l0 and 11 pushes cup 123 downwardly which releasesarms 112 and 113 allowing cables 127 and 129 to release, thereby freeingjaws 5 and 6 to close under the influence of resilient elements 7.

As shown at FIG. 1, string 66 is connected to cross member 89 ofjaw 6.When the connection is made between the string and the jaw, the stringis made taut so magnet 64 is pulled to the position of FIG. 4 whereinthe magnet is below reed switch 58 and spring 65 is compressed. Thestring is preferably made of a thin thread which readily breaks as jaws5 and 6 close. As soon as the string 66 breaks, the magnet is free tomove upwardly under the influence of spring 65. When magnet 64 isimmediately opposite reed switch 58, contacts 61 and 62 are magneticallyattracted to. each other, causing the contacts to close whereuponshutter 55 is operated by solenoid 57 and flashbulb 56 is simultaneouslyactuated to obtain a photograph of the bottom of the body of water fromwhich the sample is taken. Continued upward movement of the magnetactuates switch 58', as previously explained to actuate the auxiliarysignal devices. V I

It will be observed with reference to FIG. 1, that front edges 71 and 91of the respective jaws extend at an acute angle to the surface of bottom177 upon initial impact of the sampler with the bottom. As soon as jawactuating mechanism 8 is released, the resilient elements initiateclosing of the jaws, and weights ]2 and 13 exert downwardly actingforces which assist the initial closing of the jaws into bottom 177. Asthe jaws dig into the bottom, sacks 98 and 101 begin to fill and areforced outwardly beyond the rear faces of the jaws thereby unseatingweights 12 and'13 which merely roll out,of the cradles in the respectivejaws. As soon as weights l2 and 13 are displacedfrom the jaws, thebuoyant for ce of spheres9-11 tends to lift thesampler. Thus, as jawsSand 6 close under the forces from resil ient elements 7, a substantialpull is applied to the sampler which pulls the sample between the jawsfree from the'bottom and then returns the sampler to the surface.Cutters and engage each'other whenthe jaws are closed, and front'edges71 and 91 oppose each other. When sampler 1 reaches the surface, flare14 tires in the. manner previously describedto indicate that the sampleris surfaced. The sampler is then recovered and the bottom sample in thejaws can be examined.

With reference to the modified embodiment of the sampler shown at FIGS.5 and 6, when the sampler engages the bottom, the points 74 and 91' ofthe jaws 5 and 6 sink slightly into bottom 177 as does point 19' of baseplate 15'. In addition, the sloping edges 87 and 91 ofjaw 6' and theslopong edges 72 and 73 ofjaw 5' cooperate with the sloping edges 17'andl9' of the base to provide an inherently stable base which virtuallyeliminates any possibility of tipping of the sampler even where bottom177 slopes substantially. As shown at FIG. 6, when jaws 5' and 6' closeedges 72' and 89' are in abutting relationship to each other andcorrespondingly oppose each other in addition, the cutters 80 and 90engage each other so that a substantial area within the jaws is closedagainst lost of the sample taken when the jaws close. As jaws and 6'were moving to the position of FIG. 6 the portion of bottom 177 slicedby the jaws cause bulging of bags 98 and 101 with the result thatweights l2 and 13 were forced out of the cradles and rolled to one sideof the opening 178 formed by the jaws. I

To rouse the sampler, it is merely necessary to provide new weights l2and 13, reload camera 54, and provide a new flare assembly 14. Then, thejaws are reopened, held in position by operating assembly 8 aspreviously described, and the sampler is again dropped into the waterwhere it performs the same bottom sampling operation just described.

While a preferred embodiment of the sampler of this invention has beenshown and described, it is to be understood that numerous changes andmodifications are contemplated. For example, while the backs ofthe jawsare shown closed with a flexible member or web which may be eitherimperforate or of meshed material, a sheet metal plate suitably formedto permit accommodating the weights l2 and 13 in their respectivecradles may also be used to close the backs of the jaws. In addi tion,it is contemplated thatflotation devices other than hollow spheres l0and 11 for example, solid spheres or blocks can be used to providebuoyancy for the sam-v pler. In addition, plastics impregnated withgases or having air cells therein may be used to provide the desiredbuoyancy. Also, suitable bracing can be provided within hollow spheres10 and 11 or these spheres can be filled with a low density liquid toprevent implosion.

Thus, while some of the contemplated changes that can be made in thepreferred embodiment without departing from the scope of the inventionas herein contemplated have been listed above, it is intended that thescope of the invention shall be as defined herein and in the appendedclaims.

What is claimed is:

l. A free fall recoverable device for obtaining a picture of the bottomof a body of combination a frame;

buoyant means carried by said frame;

. releasable ballast means carried by said frame;

said device, with said ballast means, exhibiting negative buoyancy,whereby said device will sink to the bottom of the body-of waterj whenreleased from the surface;

said device,'withoutballast means, exhibiting positive 'buoyance,whereby said device will return to the surface of the body of water whenthe ballast means is released; 1

a sealed housing carried by said frame, said housing having l atransparent wall portion, and a wall portion of non-magnetic material;

a camera within said housing and positioned to obtain a picture throughsaid transparent wall portron;

camera operating means within said housing and including a magneticallyresponsive actuating element adjacent the inside of said wall portion ofnon-magnetic material; means outside said housing to operate saidactuating element, said means comprising water comprising, in

a magnet at the outside of said wall portion of nonmagnetic material andpositioned adjacent said actuating element;

magnet operating means responsive to impact of said re-coverable devicewith the bottom of the body of water to cause said magnet to operatesaid actuating element; and

means for releasing said ballast means in response to impact of therecoverable device with the bottom of the body of water;

whereby, the device returns to the surface of the body of water byvirtue of its positive bouyancy after a picture is taken and the'ballastmeans is re leased.

2. A device according to claim 1 wherein said sealed housing is fixed tosaid frame, and said camera is fixed in said housing;

a flash unit is secured in said housing; and

said camera operating means operates said flash unit in synchronism withthe camera.

3. A device according to :claim 2 wherein said magnetically responsiveactuating element is a magnetically operable switch;

said camera operating means includes said magnetically operable switch,

a solenoid operably associated-with said camera and electricallyconnected to said switch, and

electrical energy storing means to operate said solenoid in response'tooperation of said switch.

4. A device according to claim 3 wherein said magnet is a permanentmagnet;

said switch is normally open;.and

said magnet operating means, in response to impact of said recoverabledevice with the bottom of the body of water, moves said magnet to aposition to close said normally open switch.

5. A device according to claim 4 wherein said electrical energystoringmean is a battery. 1 t

6. A device according to claim 1 wherein said magnet isa permanentmagnet;

guide means are carried by said-frame at a location adjacent said wallportion of non-magnetic material. to guide said magnetalong apredetermined path; and

said magnet operating means, responsive to impact of the device with:thebottom of the body of water, moves said magnetialong said guidemeans.

7. A device according to claim l'whereinsaid frame is verticallyelongated;

said buoyant means carriedby said-frame includes a hollow sphereadjacent the upper end of the frame; :and

said releasable ballast means includes a weight adjacent the lower endof the-frame.

8. A free fall recoverable device for obtaining a picture of the bottomof a body of water at substantial underwater depths comprising, incombination I a frame; 1

means defining a sealed high pressure resistant housing carried by saidframe, said housing having a transparent wall portion a camera withinsaid housing, said camera having a shutter, and a lens within thehousing; v

means for mounting the camera in the housing to take an underwaterphotographthrough said transparent wall portion;

circuit means within said housing to operate the shutter of said camera,said circuit means including switch means within said housing saidswitch being operable to a first condition in which the circuit means isin an energized condition and the shutter is operated, and a secondcondition in which the circuit means is in an unenergized condition;switch operating means outside said housing and completely isolated fromsaid circuit means, both electrically and mechanically to operate saidswitch means to said first position in response to engagement of saidrecoverable device with the bottom of the body of water; said switchoperating means including a switch operating element adjacent theoutside of the housing and moveable along a predetermined path inresponse to engage-ment of the recoverable device with the bottom of thebody of water; said switch means including means mounted on the insideof the housing along the path of travel of the switch operating elementand responsive to a physical characteristic of the switch operatingelement so that movement of the switch operating element along its pathoperates the switch means from one of its conditions to the other;whereby, said recoverable device is particularly characterized by theabsence of mechanical and electrical connections from the outside of thehousing to the inside of the housing, to operate the shutter of thecamera. 9. A device according to claim 8 wherein said operating meansincludes resilient means, and means normally restraining said resilientmeans and releasable in response to engagement of the device with thebottom of the body of water. 10. A device according to claim 9 whereinsaid resilient means includes at least one elastic band.

11. An underwater camera arrangement for obtaining an undistortedunderwater picture and capable of use in deep water at substantialpressures comprising in combination, I I a sealed housing having acurved transparent wall and resistant to substantial external pressure;a chamber insidethe housing and defined in part by an inside surface ofthe curved wall, the chamber comprising a flat transparent plateextending across an inside surface of the curved wall,

means securing the plate to the inside surface of the curved wall insealed relation to the wall, and

a transparent liquid within the chamber and contacting substantialportions of the surfaces of the curved wall and plate defining thechamber, the liquid having an index of refraction approximately the sameas the index of refraction of water;

a camera within the enclosure and outside the chamber defined by theflat plate and curved wall;

means mounting-the camera with its lens axis generally perpendicular tothe flat wall to obtain a photograph through the flat wall, transparentliquid, and curved wall;

whereby a photograph taken by the camera when the housing is underwater,is essentially undistorted.

12. An underwater camera arrangement according to claim 11 wherein alight source is positioned within the enclosure in spaced relation tothe camera lens to illuminate the region to be photographed by thecamera;

light emitted by the light source passes through a region of the plate,transparent liquid, and curved wall which is spaced from the lens axis;and

an optically black strut extends between the transparent plate and thecurved wall to isolate the portion of the chamber through which lightfrom the source passes from the portion of the chamber through which thelens axis of the camera passes.

13. A free fall recoverable device for obtaining a picture'of the bottomof a body of water comprising, in combination a frame;

buoyant means carried by said frame;

releasable ballast means carried by said frame;

said device, with said ballast means, exhibiting negative buoyancy,whereby said 'device will return to the surface of the body of waterafter release of the ballast means;

a sealed housing carried by said frame, said housing having atransparent wall portion, and a wall portion of non-magnetic material;

a camera within said housing and positioned to obtain a picture throughsaid transparent wall portion;

camera operating means within said housing and including a magneticallyresponsive actuating element adjacent the inside of said wall portion ofnon-magnetic material;

means outside said housing to operate said actuating element, said meanscomprising a permanent magnet at the outside of said wall portion ofnon-magnetic material and positioned adjacent said actuating element,and g guide means carried by the frame at a location ad jacent thenon-magnetic material wall portion to guide the magnet along apredetermined path;

magnet operating means responsive to impact of said recoverable devicewith thebottom of the body of water to move said magnet along the guidemeans to operate said actuating element, said magnet operating meansincluding resilient means urging the magnet operating means toward aposition in'which said magnet is oper ated, and

latch means responsive to impact with the bottom of the body of water torelease said operating means.

14. A free fall recoverable device according to claim '1 wherein i saidmeans for releasing the ballast means and said magnet operating meansinclude a common latch responsive to impact of the free fall device withthe bottom of the body of water to actuate both said means. t

15. An underwater camera arrangement for obtaining an undistortedunderwater picture and capable of use in deep water at substantialpressures comprising, in combination,

a sealed housing having a curved transparent wall and resistant tosubstantial external pressure;

a chamber inside the housing and defined in part by an inside surface ofthe curved wall, the chamber comprising a flat transparent plateextending across an inside surface of the curved wall, means securingthe plate to the inside surface of the curved wall in sealed relation tothe wall, and

a transparent liquid within the chamber and cona second chamber isdefined in part by an outside surface of the curved wall of the housing,the second chamber comprising a second flat transparent plate extendingacross an outside surface of the curved wall in parallel opposedrelation to the first mentioned flat plate,

means securing the second plate to the outside of the curved wall todefine the second sealed chamber, and

a transparent liquid within the secondchamber and completely fillingthesecond chamber, the transparent liquid having an index of refractionapproximating the index of refraction of the material of the curvedtransparent wall;

whereby a photograph taken by the camera, when the housing isunderwater, is essentially undistorted.

1. A free fall recoverable device for obtaining a picture of the bottomof a body of water comprising, in combination a frame; buoyant meanscarried by said frame; releasable ballast means carried by said frame;said device, with said ballast means, exhibiting negative buoyancy,whereby said device will sink to the bottom of the body of water whenreleased from the surface; said device, without ballast means,exhibiting positive buoyance, whereby said device will return to thesurface of the body of water when the ballast means is released; asealed housing carried by said frame, said housing having a transparentwall portion, and a wall portion of non-magnetic material; a camerawithin said housing and positioned to obtain a picture through saidtransparent wall portion; camera operating means within said housing andincluding a magnetically responsive actuating element adjacent theinside of said wall portion of non-magnetic material; means outside saidhousing to operate said actuating element, said means comprising amagnet at the outside of said wall portion of non-magnetic material andpositioned adjacent said actuating element; magnet operating meansresponsive to impact of said re-coverable device with the bottom of thebody of water to cause said magnet to operate said actuating element;and means for releasing said ballast means in response to impact of therecoverable device with the bottom of the body of water; whereby, thedevice returns to the surface of the body of water by virtue of itspositive bouyancy after a picture is taken and the ballast means isreleased.
 2. A device according to claim 1 wherein said sealed housingis fixed to said frame, and said camera is fixed in said housing; aflash unit is secured in said housing; and said camera operating meansoperates said flash unit in synchronism with the camera.
 3. A deviceaccording to claim 2 wherein said magnetically responsive actuatingelement is a magnetically operable switch; said camera operating meansincludes said magnetically operable switch, a solenoid operablyassociated with said camera and electrically connected to said switch,and electRical energy storing means to operate said solenoid in responseto operation of said switch.
 4. A device according to claim 3 whereinsaid magnet is a permanent magnet; said switch is normally open; andsaid magnet operating means, in response to impact of said recoverabledevice with the bottom of the body of water, moves said magnet to aposition to close said normally open switch.
 5. A device according toclaim 4 wherein said electrical energy storing means is a battery.
 6. Adevice according to claim 1 wherein said magnet is a permanent magnet;guide means are carried by said frame at a location adjacent said wallportion of non-magnetic material to guide said magnet along apredetermined path; and said magnet operating means, responsive toimpact of the device with the bottom of the body of water, moves saidmagnet along said guide means.
 7. A device according to claim 1 whereinsaid frame is vertically elongated; said buoyant means carried by saidframe includes a hollow sphere adjacent the upper end of the frame; andsaid releasable ballast means includes a weight adjacent the lower endof the frame.
 8. A free fall recoverable device for obtaining a pictureof the bottom of a body of water at substantial underwater depthscomprising, in combination a frame; means defining a sealed highpressure resistant housing carried by said frame, said housing having atransparent wall portion; a camera within said housing, said camerahaving a shutter, and a lens within the housing; means for mounting thecamera in the housing to take an underwater photograph through saidtransparent wall portion; circuit means within said housing to operatethe shutter of said camera, said circuit means including switch meanswithin said housing said switch being operable to a first condition inwhich the circuit means is in an energized condition and the shutter isoperated, and a second condition in which the circuit means is in anunenergized condition; switch operating means outside said housing andcompletely isolated from said circuit means, both electrically andmechanically to operate said switch means to said first position inresponse to engagement of said recoverable device with the bottom of thebody of water; said switch operating means including a switch operatingelement adjacent the outside of the housing and moveable along apredetermined path in response to engage-ment of the recoverable devicewith the bottom of the body of water; said switch means including meansmounted on the inside of the housing along the path of travel of theswitch operating element and responsive to a physical characteristic ofthe switch operating element so that movement of the switch operatingelement along its path operates the switch means from one of itsconditions to the other; whereby, said recoverable device isparticularly characterized by the absence of mechanical and electricalconnections from the outside of the housing to the inside of thehousing, to operate the shutter of the camera.
 9. A device according toclaim 8 wherein said operating means includes resilient means, and meansnormally restraining said resilient means and releasable in response toengagement of the device with the bottom of the body of water.
 10. Adevice according to claim 9 wherein said resilient means includes atleast one elastic band.
 11. An underwater camera arrangement forobtaining an undistorted underwater picture and capable of use in deepwater at substantial pressures comprising, in combination, a sealedhousing having a curved transparent wall and resistant to substantialexternal pressure; a chamber inside the housing and defined in part byan inside surface of the curved wall, the chamber comprising a flattransparent plate extending across an inside surface of the curved wall,means securing the plate to The inside surface of the curved wall insealed relation to the wall, and a transparent liquid within the chamberand contacting substantial portions of the surfaces of the curved walland plate defining the chamber, the liquid having an index of refractionapproximately the same as the index of refraction of water; a camerawithin the enclosure and outside the chamber defined by the flat plateand curved wall; means mounting the camera with its lens axis generallyperpendicular to the flat wall to obtain a photograph through the flatwall, transparent liquid, and curved wall; whereby a photograph taken bythe camera when the housing is underwater, is essentially undistorted.12. An underwater camera arrangement according to claim 11 wherein alight source is positioned within the enclosure in spaced relation tothe camera lens to illuminate the region to be photographed by thecamera; light emitted by the light source passes through a region of theplate, transparent liquid, and curved wall which is spaced from the lensaxis; and an optically black strut extends between the transparent plateand the curved wall to isolate the portion of the chamber through whichlight from the source passes from the portion of the chamber throughwhich the lens axis of the camera passes.
 13. A free fall recoverabledevice for obtaining a picture of the bottom of a body of watercomprising, in combination a frame; buoyant means carried by said frame;releasable ballast means carried by said frame; said device, with saidballast means, exhibiting negative buoyancy, whereby said device willreturn to the surface of the body of water after release of the ballastmeans; a sealed housing carried by said frame, said housing having atransparent wall portion, and a wall portion of non-magnetic material; acamera within said housing and positioned to obtain a picture throughsaid transparent wall portion; camera operating means within saidhousing and including a magnetically responsive actuating elementadjacent the inside of said wall portion of non-magnetic material; meansoutside said housing to operate said actuating element, said meanscomprising a permanent magnet at the outside of said wall portion ofnon-magnetic material and positioned adjacent said actuating element,and guide means carried by the frame at a location adjacent thenon-magnetic material wall portion to guide the magnet along apredetermined path; magnet operating means responsive to impact of saidrecoverable device with the bottom of the body of water to move saidmagnet along the guide means to operate said actuating element, saidmagnet operating means including resilient means urging the magnetoperating means toward a position in which said magnet is operated, andlatch means responsive to impact with the bottom of the body of water torelease said operating means.
 14. A free fall recoverable deviceaccording to claim 1 wherein said means for releasing the ballast meansand said magnet operating means include a common latch responsive toimpact of the free fall device with the bottom of the body of water toactuate both said means.
 15. An underwater camera arrangement forobtaining an undistorted underwater picture and capable of use in deepwater at substantial pressures comprising, in combination, a sealedhousing having a curved transparent wall and resistant to substantialexternal pressure; a chamber inside the housing and defined in part byan inside surface of the curved wall, the chamber comprising a flattransparent plate extending across an inside surface of the curved wall,means securing the plate to the inside surface of the curved wall insealed relation to the wall, and a transparent liquid within the chamberand contacting substantial portions of the surfaces of the curved walland plate defining the chamber, the liquid having an index of refractiOnapproximating the index of refraction of the curved portion of thetransparent wall; a camera within the enclosure and outside the chamberdefined by the flat plate and curved wall; means mounting the camerawith its lens axis generally perpendicular to the flat wall to obtain aphotograph through the flat wall, transparent liquid, and curved wall; asecond chamber is defined in part by an outside surface of the curvedwall of the housing, the second chamber comprising a second flattransparent plate extending across an outside surface of the curved wallin parallel opposed relation to the first mentioned flat plate, meanssecuring the second plate to the outside of the curved wall to definethe second sealed chamber, and a transparent liquid within the secondchamber and completely filling the second chamber, the transparentliquid having an index of refraction approximating the index ofrefraction of the material of the curved transparent wall; whereby aphotograph taken by the camera, when the housing is underwater, isessentially undistorted.